The present invention relates generally to pipeline pigs used for inspecting, maintaining and servicing piping systems and pipelines. More specifically, the present invention relates to pipeline pigs used for cleaning, namely, pigs with means for scraping and loosening debris from the inner wall of the pipe.
Pipeline pigs are frequently employed in pipelines for a variety of services and are typically constructed to move by the force of fluid flow through a pipeline. The fluid may be in the form of water, petroleum products such as gasoline, diesel fuel, crude oil, propane, and so forth, or may be in the form of gas, such as natural gas. One of the primary reasons for sending a pig through a pipeline is to clean the interior of the pipeline of foreign matter, such as paraffin, dirt, sand, rocks, welding wire ends, scale, and water.
A cleaning pig typically includes a body which is supported centrally within the pipeline, the body having an external diameter of significantly less than the internal diameter of the pipeline. To this pig body is supported discs or cups for contacting the wall of the pipeline. The cups or discs serve several purposes. First, they serve to support the pig body centrally within the pipeline. Second, at least one of the discs serves to seal the pipeline so the pig may be moved through the pipeline by the force of fluid flow. The third basic function of such discs is to contact the inner wall of the pipeline to scrape away scale or other foreign matter.
One problem with current scraping disc or cup designs is that the disc is not self-sharpening. Another problem is that the disc does not compensate for wear caused by continuous contact with the inner wall of the pipeline. Still yet another problem is that the disc does not readily conform to the inside surface of the pipeline while at the same time providing for longer wear life. Therefore, a need exists for an improved scraping disc or cup design.